Cadmoindite is an extremely rare sulfide mineral typically found as a volcanic sublimates. It is characterized by its metallic luster and dark appearance, usually identified through analytical testing rather than visual inspection by the casual collector.
Is this cadmoindite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch cadmoindite with a known reference. Cadmoindite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: black, dark brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: microscopic crystals, octahedral crystals.
Often confused with
Cadmoindite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cadmoindite leaves brown, Sphalerite leaves pale brown to pale yellow and white; luster reads adamantine on Cadmoindite and resinous to adamantine on Sphalerite.
How to tell apart: Streak differs, so Cadmoindite leaves brown, Galena leaves lead-gray; luster reads adamantine on Cadmoindite and metallic on Galena.
Often found alongside cadmoindite
Minerals reported to co-occur with cadmoindite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CdIn₂S₄
- Mohs hardness
- 3-4
- Density
- 4.864 g/cm³
- Colors
- Streak
- Brown
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Microscopic crystals, octahedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As the bottom layer in fumarolic sublimate crusts
Where rockhounds find cadmoindite
Classic worldwide localities
- Kudriavy stratovolcano, north end of Iturup Isle, southern Kuril Islands
Field-hunting tip
Where it forms: As the bottom layer in fumarolic sublimate crusts. If you start seeing pyrite, cadmian wurtzite, rhenium disulfide in float, you are in the right ground. Typical habit: microscopic crystals, octahedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cadmoindite?+
Where is cadmoindite found?+
Is cadmoindite safe to handle?+
What rocks look like cadmoindite?+
What minerals are found with cadmoindite?+
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Find cadmoindite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
